There is proposed a three-dimensional memory device having a structure in which a plurality of columnar parts including a charge storage film and a semiconductor body penetrate a plurality of electrode layers stacked with an insulator.
There is also proposed a structure in which an air gap is formed as the insulator between the electrode layers. The plurality of electrode layers stacked with the air gap are supported by the columnar parts.
There is also proposed a method for stacking a plurality of sacrificial layers with interlayer films to form a stacked body, forming the columnar parts in the stacked body, and then removing the sacrificial layers to replace them by electrode layers. After removing the sacrificial layers and before replacing them by electrode layers, the plurality of interlayer films stacked with the air gap are supported by the columnar parts.
There is also proposed a contact structure for connecting the electrode layers of the three-dimensional memory device to a control circuit. In this structure, the plurality of electrode layers are processed in a staircase shape. An air gap may be formed also in the portion of the stacked body in which the staircase structure is formed. This also requires support by the columnar parts. The contact via reaching the staircase-shaped electrode layers from above may interfere with the semiconductor body of the columnar part.